The England international, who has missed the Red Devils' last two games with a persistent groin problem, has gone away to the United States for some winter sun to recuperate.

And United manager David Moyes hopes his top scorer will be available for the trip to Chelsea on Jan. 19.

He said: "We've sent him away on a hot-weather break with his family. His groin isn't quite recovered yet so we've sent the fitness coach with him too. Hopefully we can get him fit for Chelsea but we'll see how he is."

Moyes, whose team have lost their last three games, will be without his two premier centre-forwards for the visit of Swansea.

He added: "Robin is going to be a little while. We'll do everything we can to get him back quickly.”

Without Rooney, who has scored 11 goals for United this season, and Van Persie, who has struck 10 times, Moyes only has two fit senior strikers, in Danny Welbeck and Javier Hernandez.

Nani, Marouane Fellaini and Rio Ferdinand are also sidelined for the rematch with Swansea, who won 2-1 at Old Trafford in the FA Cup on Sunday.

But Moyes was keen to point out his side recorded six successive victories before losing their last three games.

He said: "Not winning can obviously affect your confidence. But we weren't talking about confidence when we won six in a row.

"I don't think any of the Manchester United players are [hiding]. Every one of them is standing up and doing what they can. You can never ask anyone to do more than their best and the players here are doing that.''

Moyes once again repeated his observations about the difficulty of buying the right players in January.

"The plan and decisions won't change," he said. "It is difficult to get targets at this time. I have said that from day one. I have not said we wouldn't be doing it but it is difficult."